diff --git a/source/err/errorfile.go b/source/err/errorfile.go
index a8ac2d7a..0f6006b3 100644
--- a/source/err/errorfile.go
+++ b/source/err/errorfile.go
@@ -2585,6 +2585,26 @@ var ErrorCreatorMap = map[string]ErrorCreator{
 		},
 	},
 
+	"vm/cast/a": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "unable to perform cast"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "Types can only be cast between clones of the same parent, or the " +
+			       "parent itself."
+		},
+	},
+
+	"vm/cast/b": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "unable to perform cast"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "Types can only be cast between clones of the same parent, or the " +
+			       "parent itself."
+		},
+	},
+
 	"vm/div/float": {
 		Message: func(tok *token.Token, args ...any) string {
 			return "division by zero"
@@ -2603,6 +2623,71 @@ var ErrorCreatorMap = map[string]ErrorCreator{
 		},
 	},
 
+	"vm/for/type/a": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "can't range over given type"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "You can range over lists, strings, maps, sets, and enums."
+		},
+	},
+
+	"vm/for/type/b": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "can't range over given type"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "You can range over lists, strings, maps, sets, and enums."
+		},
+	},
+
+	"vm/for/type/c": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "can't range over given type"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "You can range over lists, strings, maps, sets, and enums."
+		},
+	},
+
+	"vm/for/pair": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "range should be pair of integers"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "If you're going to give the range of a list using `::`, the elements of the pair should both be integers."
+		},
+	},
+
+	"vm/func/args": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "lambda function has the wrong number of arguments"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "The arguments passed are different in number from the parameters of the function."
+		},
+	},
+
+	"vm/func/go": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "failed to convert Pipefish value"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "You're trying to apply a Go lambda function (wrapped in a Pipefish " +
+			       "lambda function), to something that Pipefish doesn't know how to convert " +
+				   "into Go."
+		},
+	},
+
+	"vm/func/types": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "function has the wrong types"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "The arguments passed are different in type from the parameters of the function."
+		},
+	},
+
 	"vm/go/type": {
 		Message: func(tok *token.Token, args ...any) string {
 			return "can't convert Go value of type " + emph(args[0]) + " to Pipefish"
@@ -2819,6 +2904,15 @@ var ErrorCreatorMap = map[string]ErrorCreator{
 		},
 	},
 
+	"vm/index/q": {
+		Message: func(tok *token.Token, args ...any) string {
+			return fmt.Sprintf("out of range: can't index value of type %v by %v", emph(args[0]), emph(args[1]))
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return fmt.Sprintf("Pipefish just can't make sense of that at all.")
+		},
+	},
+
 	"vm/label/exist": {
 		Message: func(tok *token.Token, args ...any) string {
 			return fmt.Sprintf("can't convert string %v to a label", emphStr(args[0]))
@@ -2846,6 +2940,16 @@ var ErrorCreatorMap = map[string]ErrorCreator{
 		},
 	},
 
+	"vm/mf/lhs": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "expected value of type 'list'"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "The value on the left-hand side of the operators '?>' and '>>' " +
+				   "should always be of type 'list'."
+		},
+	},
+
 	"vm/mod/int": {
 		Message: func(tok *token.Token, args ...any) string {
 			return "taking the modulus of a number by zero"
@@ -2855,6 +2959,15 @@ var ErrorCreatorMap = map[string]ErrorCreator{
 		},
 	},
 
+	"vm/oopsie": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "something unexpected has gone wrong"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "Please tell the author of Pipefish that he messed up. Thank you."
+		},
+	},
+
 	"vm/pipe/filter/bool": {
 		Message: func(tok *token.Token, args ...any) string {
 			return "right-hand side of filter expression cannot return boolean"
@@ -3017,6 +3130,43 @@ var ErrorCreatorMap = map[string]ErrorCreator{
 		},
 	},
 
+	"vm/splat/type": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "expected value of type 'list'"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "The value on the left-hand side of the splat operator '...' " +
+				   "should always be of type 'list'."
+		},
+	},
+
+	"vm/tup/first": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "trying to take the first element of an empty tuple"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "The empty tuple '()' has no first element."
+		},
+	},
+
+	"vm/tup/last": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "trying to take the last element of an empty tuple"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "The empty tuple '()' has no last element."
+		},
+	},
+
+	"vm/typecheck": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "failed typecheck"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "You placed constraints on the types of this expression which you then violated."
+		},
+	},
+
 	"vm/types/a": {
 		Message: func(tok *token.Token, args ...any) string {
 			return "No implementation of function " + emph(tok.Literal) + " exists for the given types"
@@ -3053,6 +3203,16 @@ var ErrorCreatorMap = map[string]ErrorCreator{
 		},
 	},
 
+	"vm/unwrap": {
+		Message: func(tok *token.Token, args ...any) string {
+			return "trying to unwrap something that isn't an 'error'"
+		},
+		Explanation: func(errors Errors, pos int, tok *token.Token, args ...any) string {
+			return "The 'unwrap' function converts things of type 'error' into type 'Error': " +
+			       "it doesn't work on anything else."
+		},
+	},
+
 	"vm/with/a": {
 		Message: func(tok *token.Token, args ...any) string {
 			return fmt.Sprintf("type %v found indexing list in %v expression where %v was expected", emph(args[0]), emph("with"), emph("int"))
diff --git a/source/vm/vm.go b/source/vm/vm.go
index 53415425..d5db3dfa 100644
--- a/source/vm/vm.go
+++ b/source/vm/vm.go
@@ -377,7 +377,7 @@ loop:
 					pfArg := vm.Mem[pfMemLoc]
 					goArg, ok := vm.pipefishToGo(pfArg)
 					if !ok {
-						vm.Mem[args[0]] = values.Value{values.ERROR, err.CreateErr("vm/func/go", lambda.Tok, goArg)} // If the conversion failed, the goArg will be the Pipefish value it couldn't convert.
+						vm.Mem[args[0]] = values.Value{values.ERROR, err.CreateErr("vm/func/go", lambda.Tok, goArg)} // If the conversion failed, the goArg will be the value it couldn't convert.
 						break Switch
 					}
 					goArgs = append(goArgs, reflect.ValueOf(goArg))
@@ -2043,7 +2043,7 @@ func (vm *Vm) NewIterator(container values.Value, keysOnly bool, tokLoc uint32)
 	case values.TYPE:
 		abTyp := container.V.(values.AbstractType)
 		if len(abTyp.Types) != 1 {
-			return values.Value{values.ERROR, vm.makeError("vm/for/type/a", tokLoc)}
+			return values.Value{values.ERROR, vm.makeError("vm/for/type/a", tokLoc, )}
 		}
 		typ := abTyp.Types[0]
 		if !vm.ConcreteTypeInfo[typ].IsEnum() {
@@ -2055,7 +2055,7 @@ func (vm *Vm) NewIterator(container values.Value, keysOnly bool, tokLoc uint32)
 			return values.Value{values.ITERATOR, &values.EnumIterator{Type: typ, Max: len(vm.ConcreteTypeInfo[typ].(EnumType).ElementNames)}}
 		}
 	default:
-		return values.Value{values.ERROR, vm.makeError("vm/for/type", tokLoc)}
+		return values.Value{values.ERROR, vm.makeError("vm/for/type/c", tokLoc)}
 	}
 }