global: Use requireContext rather than getContext in fragments

requireContext provides helpful error messages when it's null as opposed to getContext
which simply throws a NullPointerException.

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

app/src/main/java/com/wireguard/android/fragment/BaseFragment.java

@@ -113,12 +113,12 @@ public abstract class BaseFragment extends Fragment implements OnSelectedTunnelC
                 return;
             final String error = ErrorMessages.get(throwable);
             final int messageResId = checked ? R.string.error_up : R.string.error_down;
-            final String message = getContext().getString(messageResId, error);
+            final String message = requireContext().getString(messageResId, error);
             final View view = getView();
             if (view != null)
                 Snackbar.make(view, message, Snackbar.LENGTH_LONG).show();
             else
-                Toast.makeText(getContext(), message, Toast.LENGTH_LONG).show();
+                Toast.makeText(requireContext(), message, Toast.LENGTH_LONG).show();
             Log.e(TAG, message, throwable);
         });
     }

app/src/main/java/com/wireguard/android/fragment/TunnelDetailFragment.java

@@ -110,14 +110,14 @@ public class TunnelDetailFragment extends BaseFragment {
 
     private String formatBytes(final long bytes) {
         if (bytes < 1024)
-            return getContext().getString(R.string.transfer_bytes, bytes);
+            return requireContext().getString(R.string.transfer_bytes, bytes);
         else if (bytes < 1024*1024)
-            return getContext().getString(R.string.transfer_kibibytes, bytes/1024.0);
+            return requireContext().getString(R.string.transfer_kibibytes, bytes/1024.0);
         else if (bytes < 1024*1024*1024)
-            return getContext().getString(R.string.transfer_mibibytes, bytes/(1024.0*1024.0));
+            return requireContext().getString(R.string.transfer_mibibytes, bytes/(1024.0*1024.0));
         else if (bytes < 1024*1024*1024*1024)
-            return getContext().getString(R.string.transfer_gibibytes, bytes/(1024.0*1024.0*1024.0));
-        return getContext().getString(R.string.transfer_tibibytes, bytes/(1024.0*1024.0*1024.0)/1024.0);
+            return requireContext().getString(R.string.transfer_gibibytes, bytes/(1024.0*1024.0*1024.0));
+        return requireContext().getString(R.string.transfer_tibibytes, bytes/(1024.0*1024.0*1024.0)/1024.0);
     }
 
     private void updateStats() {
@@ -153,7 +153,7 @@ public class TunnelDetailFragment extends BaseFragment {
                     peer.transferText.setVisibility(View.GONE);
                     continue;
                 }
-                peer.transferText.setText(getContext().getString(R.string.transfer_rx_tx, formatBytes(rx), formatBytes(tx)));
+                peer.transferText.setText(requireContext().getString(R.string.transfer_rx_tx, formatBytes(rx), formatBytes(tx)));
                 peer.transferLabel.setVisibility(View.VISIBLE);
                 peer.transferText.setVisibility(View.VISIBLE);
             }

app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java

@@ -61,7 +61,7 @@ public class TunnelEditorFragment extends BaseFragment implements AppExclusionLi
         if (throwable == null) {
             message = getString(R.string.config_save_success, savedTunnel.getName());
             Log.d(TAG, message);
-            Toast.makeText(getContext(), message, Toast.LENGTH_SHORT).show();
+            Toast.makeText(requireContext(), message, Toast.LENGTH_SHORT).show();
             onFinished();
         } else {
             final String error = ErrorMessages.get(throwable);
@@ -207,7 +207,7 @@ public class TunnelEditorFragment extends BaseFragment implements AppExclusionLi
             tunnel = newTunnel;
             message = getString(R.string.tunnel_create_success, tunnel.getName());
             Log.d(TAG, message);
-            Toast.makeText(getContext(), message, Toast.LENGTH_SHORT).show();
+            Toast.makeText(requireContext(), message, Toast.LENGTH_SHORT).show();
             onFinished();
         } else {
             final String error = ErrorMessages.get(throwable);