Do not catch InternalCompilerErrors as part of fatal error handling.

InternalCompilerErrors always have to end the whole compilation process because a serious inconsistency was detected.

libsolidity/Parser.cpp

@@ -88,12 +88,10 @@ ASTPointer<SourceUnit> Parser::parse(shared_ptr<Scanner> const& _scanner)
 		}
 		return nodeFactory.createNode<SourceUnit>(nodes);
 	}
-	catch(FatalError const& _error)
-	{
-		return nullptr;
-	}
-	catch(Exception const& _e)
+	catch (FatalError const& _error)
 	{
+		if (m_errors.empty())
+			throw; // Something is weird here, rather throw again.
 		return nullptr;
 	}
 }