diff --git a/src/lib/addons/themes/colors/updater.ts b/src/lib/addons/themes/colors/updater.ts
index 6a3c80f..daeadd8 100644
--- a/src/lib/addons/themes/colors/updater.ts
+++ b/src/lib/addons/themes/colors/updater.ts
@@ -40,19 +40,55 @@ export function updateBunnyColor(colorManifest: ColorManifest | null, { update =
     });
 
     if (internalDef != null) {
-        tokenRef.Theme[ref.key.toUpperCase()] = ref.key;
-        FormDivider.DIVIDER_COLORS[ref.key] = FormDivider.DIVIDER_COLORS[ref.current!.reference];
+        // Register the synthetic key BEFORE calling native, and verify it actually
+        // landed in every table native reads from. If any registration step fails,
+        // bail out to a known-good theme instead of handing native an unknown key.
+        try {
+            tokenRef.Theme[ref.key.toUpperCase()] = ref.key;
 
-        Object.keys(tokenRef.Shadow).forEach(k => tokenRef.Shadow[k][ref.key] = tokenRef.Shadow[k][ref.current!.reference]);
-        Object.keys(tokenRef.SemanticColor).forEach(k => {
-            tokenRef.SemanticColor[k][ref.key] = {
-                ...tokenRef.SemanticColor[k][ref.current!.reference]
-            };
-        });
+            if (!FormDivider.DIVIDER_COLORS[ref.current!.reference]) {
+                throw new Error(`Missing divider color reference: ${ref.current!.reference}`);
+            }
+            FormDivider.DIVIDER_COLORS[ref.key] = FormDivider.DIVIDER_COLORS[ref.current!.reference];
+
+            Object.keys(tokenRef.Shadow).forEach(k => {
+                if (!(ref.current!.reference in tokenRef.Shadow[k])) {
+                    throw new Error(`Missing shadow reference: ${ref.current!.reference}`);
+                }
+                tokenRef.Shadow[k][ref.key] = tokenRef.Shadow[k][ref.current!.reference];
+            });
+
+            Object.keys(tokenRef.SemanticColor).forEach(k => {
+                if (!(ref.current!.reference in tokenRef.SemanticColor[k])) {
+                    throw new Error(`Missing semantic color reference: ${ref.current!.reference}`);
+                }
+                tokenRef.SemanticColor[k][ref.key] = {
+                    ...tokenRef.SemanticColor[k][ref.current!.reference]
+                };
+            });
+        } catch (e) {
+            console.error("Failed to register custom theme key, falling back", e);
+            ref.current = null; // force fallback path below
+        }
     }
 
     if (update) {
         AppearanceManager.setShouldSyncAppearanceSettings(false);
-        AppearanceManager.updateTheme(internalDef != null ? ref.key : ref.lastSetDiscordTheme);
+
+        const targetTheme = ref.current != null ? ref.key : ref.lastSetDiscordTheme;
+
+        // This is the actual crash site: a raw call into native code with no
+        // guard. Wrap it so a native-side rejection can't take the whole
+        // bridge/thread down — fall back to the last known-good Discord theme.
+        try {
+            AppearanceManager.updateTheme(targetTheme);
+        } catch (e) {
+            console.error(`Native rejected theme "${targetTheme}", reverting to "${ref.lastSetDiscordTheme}"`, e);
+            try {
+                AppearanceManager.updateTheme(ref.lastSetDiscordTheme);
+            } catch (e2) {
+                console.error("Fallback theme also failed to apply", e2);
+            }
+        }
     }
 }