don't crash if rosetta is not available on macOS (#1366)

* don't crash if rosetta is not available on macOS

* make error a dialog

* add newlines

* fix format

* modify strings

kindlecomicconverter/KCC_gui.py

@@ -1189,6 +1189,11 @@ class KCCGUI(KCC_ui.Ui_mainWindow):
             self.kindleGen = False
             if startup:
                 self.display_kindlegen_missing()
+        except OSError as e:
+            self.kindleGen = False
+            if startup:
+                error = f"kindlegen: {e.strerror}\n\n Re-install Rosetta/Kindle Previewer/other Intel app?\n\nPlease email Amazon to make Kindle Previewer Apple silicon native at amazon.com/kindle-help"
+                self.showDialog(error, 'error')
 
     def __init__(self, kccapp, kccwindow):
         global APP, MW, GUI

kindlecomicconverter/comic2ebook.py

@@ -1673,6 +1673,11 @@ def checkTools(source):
         except (FileNotFoundError, CalledProcessError):
             print('ERROR: KindleGen is missing!')
             sys.exit(1)
+        except OSError as e:
+            print(f"kindlegen: {e.strerror}")
+            print('Re-install Rosetta/Kindle Previewer/other Intel app?')
+            print('Please email Amazon to make Kindle Previewer Apple silicon native at amazon.com/kindle-help')
+            sys.exit(1)
 
 
 def checkPre(source='KCC-'):