Simplify handling synchronously resolved promises [refactor]

lib/renderer.js

@@ -323,64 +323,62 @@ class PartialRenderer extends ReactDOMServerRenderer {
 		const {stack} = this;
 		const frame = this.stackPopOriginal.call(stack);
 
-		// Add node to tree
-		const node = this.createChildWithStackState(TYPE_PROMISE, frame);
-		node.element = element;
-		node.promise = promise;
-		node.resolved = false;
-
 		// Follow promise
-		this.numAwaiting++;
-
-		let sync = true, resolvedSync = false;
+		let node;
 		promise.then(
 			() => {
-				// If node is no longer going to be rendered because boundary
-				// fallback above has already triggered, ignore result.
-				// Also ignore if callback called more than once.
-				if (node.resolved) return;
-				node.resolved = true;
-
 				// Handle synchronous callback
-				if (sync) {
-					resolvedSync = true;
+				if (!node) {
+					node = {resolved: true};
 					return;
 				}
 
 				this.resolved(node);
 			},
 			err => {
-				// Swallow errors where node is not going to be rendered
-				if (node.resolved) return;
-				node.resolved = true;
-
-				// Promise is no longer awaited
-				this.numAwaiting--;
+				// Handle synchronous callback - throw error
+				if (!node) {
+					node = {resolved: true};
+					throw err;
+				}
 
-				// Abort all rendering
-				this.halt(err);
+				this.rejected(node, err);
 			}
 		);
-		sync = false;
 
 		// If Promise resolved synchronously, push element back onto stack so it renders again
-		if (resolvedSync) {
-			// Push element onto stack
-			frame.children = toArray(element);
-			stack.push(frame);
+		if (node) {
+			// Create tree node and step into it
+			node = this.createChild(TYPE_PROMISE);
+			node.resolved = true;
 
-			// Step into this node
 			node.frame = frame;
 			this.node = node;
 			this.nonDomFrames++;
 
-			// Promise is no longer awaited
-			this.numAwaiting--;
+			// Push element onto stack
+			frame.children = toArray(element);
+			stack.push(frame);
+
+			return;
 		}
+
+		// Awaiting promise - create tree node
+		node = this.createChildWithStackState(TYPE_PROMISE, frame);
+		node.element = element;
+		node.promise = promise;
+		node.resolved = false;
+
+		this.numAwaiting++;
 	}
 
 	resolved(node) {
+		// If node is no longer going to be rendered because boundary
+		// fallback above has already triggered, ignore result.
+		if (node.resolved) return;
+
 		// Promise is no longer awaited
+		node.resolved = true;
 		this.numAwaiting--;
 
 		// Step into node and reinstate stack state with element on stack ready to render
@@ -395,6 +393,19 @@ class PartialRenderer extends ReactDOMServerRenderer {
 		this.resetProviders();
 	}
 
+	rejected(node, err) {
+		// If node is no longer going to be rendered because boundary
+		// fallback above has already triggered, swallow error.
+		if (node.resolved) return;
+
+		// Promise is no longer awaited
+		node.resolved = true;
+		this.numAwaiting--;
+
+		// Abort all rendering
+		this.halt(err);
+	}
+
 	restoreStack(stackState, element) {
 		// Reinstate stack state with element on stack ready to render
 		const frame = {