Fix NPE with converter when computeClassMatches

1 files changed, 18 insertions, 15 deletions

diff --git a/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaWriter.java b/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaWriter.java
index 95896898..c09f4a67 100644
--- a/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaWriter.java
+++ b/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaWriter.java
@@ -59,24 +59,27 @@ public class MappingsEnigmaWriter {
                 }
 
                 // Remove dropped mappings
-                List<ClassMapping> droppedClassMappings = new ArrayList<>(mappings.getPreviousState().classes());
-                List<ClassMapping> classMappings = new ArrayList<>(mappings.classes());
-                droppedClassMappings.removeAll(classMappings);
-                for (ClassMapping classMapping : droppedClassMappings)
+                if (mappings.getPreviousState() != null)
                 {
-                        File obFile = new File(target, classMapping.getObfFullName() + ".mapping");
-                        File result;
-                        if (classMapping.getDeobfName() == null)
-                                result = obFile;
-                        else
+                        List<ClassMapping> droppedClassMappings = new ArrayList<>(mappings.getPreviousState().classes());
+                        List<ClassMapping> classMappings = new ArrayList<>(mappings.classes());
+                        droppedClassMappings.removeAll(classMappings);
+                        for (ClassMapping classMapping : droppedClassMappings)
                         {
-                                // Make sure that old version of the file doesn't exist
-                                if (obFile.exists())
-                                        obFile.delete();
-                                result = new File(target, classMapping.getDeobfName() + ".mapping");
+                                File obFile = new File(target, classMapping.getObfFullName() + ".mapping");
+                                File result;
+                                if (classMapping.getDeobfName() == null)
+                                        result = obFile;
+                                else
+                                {
+                                        // Make sure that old version of the file doesn't exist
+                                        if (obFile.exists())
+                                                obFile.delete();
+                                        result = new File(target, classMapping.getDeobfName() + ".mapping");
+                                }
+                                if (result.exists())
+                                        result.delete();
                         }
-                        if (result.exists())
-                                result.delete();
                 }
         }