app: Show stacktrace on exception when "--debug" is Truebschubert/debug-show-trace

Previously we would have the exceptions making debugging quite harder.

When requesting '--debug', it seems ok to show the stack trace that
created the error

1 files changed, 11 insertions, 1 deletions

diff --git a/src/buildstream/_frontend/app.py b/src/buildstream/_frontend/app.py
index 379ed4b7f..a5588e672 100644
--- a/src/buildstream/_frontend/app.py
+++ b/src/buildstream/_frontend/app.py
@@ -706,7 +706,17 @@ class App():
     #
     def _error_exit(self, error, prefix=None):
         click.echo("", err=True)
-        main_error = str(error)
+
+        if self.context is None or self.context.log_debug is None:  # Context might not be initialized, default to cmd
+            debug = self._main_options["debug"]
+        else:
+            debug = self.context.log_debug
+
+        if debug:
+            main_error = "\n\n" + traceback.format_exc()
+        else:
+            main_error = str(error)
+
         if prefix is not None:
             main_error = "{}: {}".format(prefix, main_error)