Don't check overlay hash for overlays that didn't exist before (#2136)

runelite-mixins/src/main/java/net/runelite/mixins/RSAbstractArchiveMixin.java

@@ -50,6 +50,9 @@ public abstract class RSAbstractArchiveMixin implements RSAbstractArchive
 		final Logger log = client.getLogger();
 		final String path = String.format("/runelite/%s/%s", archiveId, groupId);
 
+		// rsData will be null if this script didn't exist at first
+		if (rsData != null)
+		{
 			String overlayHash, originalHash;
 
 			try (final InputStream hashIn = getClass().getResourceAsStream(path + ".hash"))
@@ -71,6 +74,7 @@ public abstract class RSAbstractArchiveMixin implements RSAbstractArchive
 				overlayOutdated = true;
 				return rsData;
 			}
+		}
 
 		try (final InputStream ovlIn = getClass().getResourceAsStream(path))
 		{