[processing] Always log python exceptions to logger

nyalldawson · nyalldawson · commit 2a6feeeb682d · 2018-04-06T14:19:09.000+10:00
Because Python code cannot catch and rethrow c++ exceptions without losing context, we end up getting unknown exceptions caught by c++ from python code (phew!). So if we catch a python exception from processing, throw it into the log so at least there's the full debugging detail available on the console. (Not ideal. Would love to see a PR allowing the full error message to be passed correctly between c++/python/back again) (cherry-picked from f4445a0)
diff --git a/python/core/core.sip.in b/python/core/core.sip.in
@@ -6,6 +6,7 @@ ${DEFAULTDOCSTRINGSIGNATURE}
 %ModuleCode
 
 #include "qgsexception.h"
+#include "qgslogger.h"
 
 QString getTraceback()
 {
@@ -107,6 +108,7 @@ done:
 
 %VirtualErrorHandler processing_exception_handler
     QString trace = getTraceback();
+    QgsLogger::critical( trace );
     SIP_RELEASE_GIL( sipGILState );
     throw QgsProcessingException( trace );
 %End
