import sys
import platform
import traceback
import webbrowser

from PyQt5.QtCore import QT_VERSION_STR, PYQT_VERSION_STR, QCoreApplication
from PyQt5.QtWidgets import QDialog, QDialogButtonBox, QVBoxLayout, QLabel, QTextEdit
from UM.i18n import i18nCatalog
catalog = i18nCatalog("cura")

debug_mode = False

def show(exception_type, value, tb):
    if QCoreApplication.instance() and QCoreApplication.instance().getCommandLineOption("debug-mode", False):
        debug_mode = True

    traceback.print_exception(exception_type, value, tb)

    if not debug_mode:
        return

    application = QCoreApplication.instance()
    if not application:
        sys.exit(1)

    dialog = QDialog()
    dialog.setWindowTitle(catalog.i18nc("@title:window", "Oops!"))

    layout = QVBoxLayout(dialog)

    label = QLabel(dialog)
    layout.addWidget(label)
    label.setText(catalog.i18nc("@label", "<p>An uncaught exception has occurred!</p><p>Please use the information below to post a bug report at <a href=\"http://github.com/Ultimaker/Cura/issues\">http://github.com/Ultimaker/Cura/issues</a></p>"))

    textarea = QTextEdit(dialog)
    layout.addWidget(textarea)

    try:
        from UM.Application import Application
        version = Application.getInstance().getVersion()
    except:
        version = "Unknown"

    trace = "".join(traceback.format_exception(exception_type, value, tb))

    crash_info = "Version: {0}\nPlatform: {1}\nQt: {2}\nPyQt: {3}\n\nException:\n{4}"
    crash_info = crash_info.format(version, platform.platform(), QT_VERSION_STR, PYQT_VERSION_STR, trace)

    textarea.setText(crash_info)

    buttons = QDialogButtonBox(QDialogButtonBox.Close, dialog)
    layout.addWidget(buttons)
    buttons.addButton(catalog.i18nc("@action:button", "Open Web Page"), QDialogButtonBox.HelpRole)
    buttons.rejected.connect(dialog.close)
    buttons.helpRequested.connect(lambda: webbrowser.open("http://github.com/Ultimaker/Cura/issues"))

    dialog.exec_()
    sys.exit(1)

@@ -285,28 +285,8 @@
 %22)%0A%0A
-debug_mode = False%0A%0A
 def 
@@ -318,16 +318,39 @@
 e, tb):%0A
+    debug_mode = False%0A
     if Q
@@ -379,12 +379,30 @@
 ce()
- and
+:%0A        debug_mode =
  QCo
@@ -471,35 +471,8 @@
 lse)
-:%0A        debug_mode = True
 %0A%0A  

Fix crash handler to not complain about debug_mode not being set