Only show stack trace in debug mode

capa/main.py

@@ -18,7 +18,8 @@
 import datetime
 import textwrap
 import contextlib
-from typing import Any, Set, Dict, List, Callable, Optional
+from types import TracebackType
+from typing import Any, Set, Dict, List, Type, Union, Callable, Optional
 from pathlib import Path
 
 import halo
@@ -112,6 +113,7 @@
 E_MISSING_CAPE_STATIC_ANALYSIS = 21
 E_MISSING_CAPE_DYNAMIC_ANALYSIS = 22
 E_EMPTY_REPORT = 23
+E_UNHANDLED = 24
 
 logger = logging.getLogger("capa")
 
@@ -978,6 +980,26 @@ def handle_common_args(args):
         args.signatures = sigs_path
 
 
+def simple_message_exception_handler(
+    exctype: Union[type[BaseException], Type[BaseException]],
+    value: BaseException,
+    traceback: TracebackType,
+):
+    """
+    if not in debug mode, prints helpful message on unhandled exceptions
+
+    args:
+      # TODO(aaronatp): Once capa drops support for Python 3.8, move this to the type annotation in the function parameters
+      exctype (type[BaseException]): exception class
+    """
+
+    print(
+        f"Unexpected exception raised: {exctype}. Please run capa in debug mode (-d/--debug) "
+        + "to see the stack trace. Please also report your issue on the capa GitHub page so we "
+        + "can improve the code! (https://github.com/mandiant/capa/issues)"
+    )
+
+
 def main(argv: Optional[List[str]] = None):
     if sys.version_info < (3, 8):
         raise UnsupportedRuntimeError("This version of capa can only be used with Python 3.8+")
@@ -1020,6 +1042,8 @@ def main(argv: Optional[List[str]] = None):
     install_common_args(parser, {"sample", "format", "backend", "os", "signatures", "rules", "tag"})
     parser.add_argument("-j", "--json", action="store_true", help="emit JSON instead of text")
     args = parser.parse_args(args=argv)
+    if not args.debug:
+        sys.excepthook = simple_message_exception_handler
     ret = handle_common_args(args)
     if ret is not None and ret != 0:
         return ret