avoid null

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/history/GitRepository.java

@@ -683,48 +683,46 @@ private org.eclipse.jgit.lib.Repository getJGitRepository(String directory) thro
         File dotGit = Paths.get(directory, Constants.DOT_GIT).toFile();
         if (dotGit.isDirectory()) {
             return FileRepositoryBuilder.create(dotGit);
-        } else if (dotGit.isFile()) {
-            // Assume this is a sub-module.
-            String gitDirValue;
-            if ((gitDirValue = getGitDirValue(dotGit)) == null) {
-                return null;
-            }
+        }
 
-            int dotGitIndex = gitDirValue.indexOf(Constants.DOT_GIT);
-            if (dotGitIndex == -1) {
-                return null;
-            }
+        // Assume this is a sub-module so dotGit is a file.
+        String gitDirValue;
+        if ((gitDirValue = getGitDirValue(dotGit)) == null) {
+            throw new IOException("cannot get gitDir value from " + dotGit);
+        }
 
-            String parentAbsPath;
-            if (Paths.get(gitDirValue).isAbsolute()) {
-                parentAbsPath = gitDirValue.substring(0, dotGitIndex - 1);
-            } else {
-                File parent = new File(directory, gitDirValue.substring(0, dotGitIndex + Constants.DOT_GIT.length()));
-                parentAbsPath = parent.getCanonicalPath();
-                int indexDotGitParent = parentAbsPath.indexOf(File.separator + Constants.DOT_GIT);
-                if (indexDotGitParent == -1) {
-                    return null;
-                }
+        int dotGitIndex = gitDirValue.indexOf(Constants.DOT_GIT);
+        if (dotGitIndex == -1) {
+            throw new IOException("no .git in " + gitDirValue);
+        }
 
-                parentAbsPath = parentAbsPath.substring(0, indexDotGitParent);
-                if (!directory.startsWith(parentAbsPath)) {
-                    return null;
-                }
+        String parentAbsPath;
+        if (Paths.get(gitDirValue).isAbsolute()) {
+            parentAbsPath = gitDirValue.substring(0, dotGitIndex - 1);
+        } else {
+            File parent = new File(directory, gitDirValue.substring(0, dotGitIndex + Constants.DOT_GIT.length()));
+            parentAbsPath = parent.getCanonicalPath();
+            int indexDotGitParent = parentAbsPath.indexOf(File.separator + Constants.DOT_GIT);
+            if (indexDotGitParent == -1) {
+                throw new IOException("not .git in " + parentAbsPath);
             }
 
-            // Assumes directory is canonical path too.
-            String directoryRelative = directory.substring(parentAbsPath.length() + 1);
-
-            Repository parentRepository = FileRepositoryBuilder.
-                    create(Paths.get(parentAbsPath, Constants.DOT_GIT).toFile());
-            if (parentRepository == null) {
-                return null;
+            parentAbsPath = parentAbsPath.substring(0, indexDotGitParent);
+            if (!directory.startsWith(parentAbsPath)) {
+                throw new IOException(directory + " does not start with " + parentAbsPath);
             }
+        }
+
+        // Assumes directory is canonical path too.
+        String directoryRelative = directory.substring(parentAbsPath.length() + 1);
 
-            return SubmoduleWalk.getSubmoduleRepository(parentRepository, directoryRelative);
+        Repository parentRepository = FileRepositoryBuilder.
+                create(Paths.get(parentAbsPath, Constants.DOT_GIT).toFile());
+        if (parentRepository == null) {
+            throw new IOException("cannot create parent repository from " + parentAbsPath);
         }
 
-        return null;
+        return SubmoduleWalk.getSubmoduleRepository(parentRepository, directoryRelative);
     }
 
     private void rebuildTagList(File directory) {