RootShell: stop if we can't start

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/util/RootShell.java

@@ -112,6 +112,7 @@ public class RootShell {
     }
 
     public synchronized void start() throws IOException, NoRootException {
+        try {
             if (isRunning())
                 return;
             if (!localBinaryDir.isDirectory() && !localBinaryDir.mkdirs())
@@ -145,6 +146,10 @@ public class RootShell {
                 }
                 throw new IOException("Shell failed to start: " + process.exitValue());
             }
+        } catch (final IOException | NoRootException e) {
+            stop();
+            throw e;
+        }
     }
 
     public synchronized void stop() throws IOException {