Fix various null pointer dereferences - #639

Check failure on line 1553 in modulemd/modulemd-module-index.c

sonarqubecloud / SonarCloud Code Analysis

Refactor this code to not nest more than 3 if|for|do|while|switch statements.

See more on https://sonarcloud.io/project/issues?id=fedora-modularity_libmodulemd&issues=AZ6yBqbVNE5g047famNb&open=AZ6yBqbVNE5g047famNb&pullRequest=639