Reports: Don't crash when report generator fails without backtrace.

Author: jralls

gnucash/report/gnc-report.cpp

@@ -227,13 +227,20 @@ gnc_run_report_with_error_handling (gint report_id, gchar ** data, gchar **errms
         *errmsg = NULL;
         return TRUE;
     }
-    else
+    else if (scm_is_string (captured_error))
     {
         *errmsg = gnc_scm_to_utf8_string (captured_error);
         *data = NULL;
         PWARN ("Error in report: %s", *errmsg);
         return FALSE;
     }
+    else
+    {
+        *data = nullptr;
+        PWARN("Report %s Failed to generate html but didn't raise a Scheme exception.",
+              gnc_report_name (report));
+        return FALSE;
+    }
 }
 
 gchar*