fix wasmImportsToPrepend overriding existing imports (#495)

* fix wasmImportsToPrepend overriding existing imports

when dealing with wasms that have more than 1 consumer, when we collect
the wasm imports to prepend for a specific edge funcion we're always
re-setting the array of wasm imports instead of appending them, this
causes edge functions to always only consider the last wasm
import, fix such issue

resolves #494

.changeset/wild-olives-invent.md

@@ -0,0 +1,12 @@
+---
+'@cloudflare/next-on-pages': patch
+---
+
+fix wasms not always getting imported when necessary
+
+Details:
+when dealing with wasms that have more than 1 consumer, when we collect
+the wasm imports to prepend for a specific edge funcion we're always
+re-setting the array of wasm imports instead of appending them, this
+causes edge functions to always only consider the last wasm
+import, the changes here fix such behavior

packages/next-on-pages/src/buildApplication/processVercelFunctions/dedupeEdgeFunctions.ts

@@ -89,7 +89,7 @@ async function processFunctionIdentifiers(
 
 		// Tracks the imports to prepend to the final code for the function and identifiers.
 		const importsToPrepend: NewImportInfo[] = [];
-		const wasmImportsToPrepend = new Map<string, string[]>();
+		const wasmImportsToPrepend = new Map<string, Set<string>>();
 
 		const newFnLocation = join('functions', `${fnInfo.relativePath}.js`);
 		const newFnPath = join(opts.nopDistDir, newFnLocation);
@@ -121,10 +121,13 @@ async function processFunctionIdentifiers(
 				if (newFilePath) identifierPathsToBuild.add(newFilePath);
 				if (newImport) importsToPrepend.push(newImport);
 				if (wasmImports.length) {
-					wasmImportsToPrepend.set(
-						identifierInfo.newDest as string,
-						wasmImports,
-					);
+					const newDest = identifierInfo.newDest as string;
+					if (!wasmImportsToPrepend.get(newDest)) {
+						wasmImportsToPrepend.set(newDest, new Set());
+					}
+					// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+					const destImports = wasmImportsToPrepend.get(newDest)!;
+					wasmImports.forEach(wasmImport => destImports.add(wasmImport));
 				}
 			}
 		}
@@ -218,7 +221,7 @@ type BuildFunctionFileOpts = {
  * @param opts Options for processing the function.
  */
 async function prependWasmImportsToCodeBlocks(
-	wasmImportsToPrepend: Map<string, string[]>,
+	wasmImportsToPrepend: Map<string, Set<string>>,
 	identifierMaps: Record<IdentifierType, IdentifiersMap>,
 	{ workerJsDir, nopDistDir }: ProcessVercelFunctionsOpts,
 ) {