Fix ICE candidate handling for Node.js compatibility

Handle both browser and Node.js (wrtc) environments when processing ICE candidates. Browsers provide toJSON() method on candidates, but wrtc library candidates are already plain objects. Check for toJSON() existence before calling it.

Fixes: TypeError: event.candidate.toJSON is not a function in Node.js

src/rondevu.ts

@@ -365,10 +365,17 @@ export class Rondevu {
         pc.onicecandidate = async (event) => {
             if (event.candidate) {
                 try {
+                    // Handle both browser and Node.js (wrtc) environments
+                    // Browser: candidate.toJSON() exists
+                    // Node.js wrtc: candidate is already a plain object
+                    const candidateData = typeof event.candidate.toJSON === 'function'
+                        ? event.candidate.toJSON()
+                        : event.candidate
+
                     await this.api.addOfferIceCandidates(
                         serviceFqn,
                         offerId,
-                        [event.candidate.toJSON()]
+                        [candidateData]
                     )
                 } catch (err) {
                     console.error('[Rondevu] Failed to send ICE candidate:', err)