Demo app: Fail fast if parsing invalid DRM config from JSON

These fields can't be used if `drm_uuid` isn't set. Make that case throw
an exception, so it's obvious to a developer what's wrong.

Most of the fields 'obviously' need `drm_uuid` to be set, but it's not
obvious for `drm_session_for_clear_content` (because it might be
reasonable to assume it's possible to play clear content without
specifying a UUID). This tripped me up in
https://github.com/google/ExoPlayer/issues/8842#issuecomment-833659808.

PiperOrigin-RevId: 397328556

demos/main/src/main/java/com/google/android/exoplayer2/demo/SampleChooserActivity.java

@@ -448,6 +448,18 @@ public class SampleChooserActivity extends AppCompatActivity
                   .setMultiSession(drmMultiSession)
                   .setForceDefaultLicenseUri(drmForceDefaultLicenseUri)
                   .build());
+        } else {
+          checkState(drmLicenseUri == null, "drm_uuid is required if drm_license_uri is set.");
+          checkState(
+              drmLicenseRequestHeaders == null,
+              "drm_uuid is required if drm_key_request_properties is set.");
+          checkState(
+              !drmSessionForClearContent,
+              "drm_uuid is required if drm_session_for_clear_content is set.");
+          checkState(!drmMultiSession, "drm_uuid is required if drm_multi_session is set.");
+          checkState(
+              !drmForceDefaultLicenseUri,
+              "drm_uuid is required if drm_force_default_license_uri is set.");
         }
         if (subtitleUri != null) {
           MediaItem.Subtitle subtitle =