Make errors in peakwidths! more friendly

src/peakwidth.jl

@@ -205,9 +205,11 @@ end
 
 function peakwidths!(pks::NamedTuple; strict=true, relheight=0.5, min=nothing, max=nothing)
     !hasproperty(pks, :proms) && throw(ArgumentError(
-        "Argument `pks` is expected to have prominences (`:proms`) already calculated"))
+        "Argument `pks` is expected to have prominences (`:proms`) already calculated. \nExample fix: `peakwidths!(peakproms!(pks))`"))
     if xor(hasproperty(pks, :widths), hasproperty(pks, :edges))
-        throw(ArgumentError("Argument `pks` is expected have neither or both of the fields `:widths` and `:edges`."))
+        hasproperty(pks, :widths) ? 
+            throw(ArgumentError("Argument `pks` is has property `:widths`, but not field `:edges`. As functions from Peaks.jl only ever add both, this implies unexpected tampering with the peaks provided. To avoid unexpected behaviour, this is an error." )) :
+            throw(ArgumentError("Argument `pks` is has property `:edges`, but not field `:widths`. As functions from Peaks.jl only ever add both, this implies unexpected tampering with the peaks provided. To avoid unexpected behaviour, this is an error." ))
     end
     if !hasproperty(pks, :widths)
         # Wait to filter until after merging `pks`