fix: Top level init bb.js, but better scoped imports to not incur cos…

…t too early (#3629)

Related to this issue:
AztecProtocol/aztec-packages#3618
Gets `aztec-cli help` down to 0.01s!!!!

ts/scripts/cjs_postprocess.sh

@@ -11,4 +11,6 @@ DIR="./dest/node-cjs"
 for FILE in $(find "$DIR" -name "*.js"); do
     # Use sed to replace 'import.meta.url' with '""'
     sed -i.bak 's/import\.meta\.url/""/g' "$FILE" && rm "$FILE.bak"
+    # Use sed to remove any lines postfixed // POSTPROCESS ESM ONLY
+    sed -i.bak '/\/\/ POSTPROCESS ESM ONLY$/d' "$FILE" && rm "$FILE.bak"
 done

ts/src/barretenberg/index.ts

@@ -65,7 +65,7 @@ export class BarretenbergSync extends BarretenbergApiSync {
 
   static getSingleton() {
     if (!barretenbergSyncSingleton) {
-      throw new Error('Initialise first via initSingleton().');
+      throw new Error('First call BarretenbergSync.initSingleton() on @aztec/bb.js module.');
     }
     return barretenbergSyncSingleton;
   }
@@ -75,10 +75,8 @@ export class BarretenbergSync extends BarretenbergApiSync {
   }
 }
 
-// If we're loading this module in a test environment, just init the singleton immediately for convienience.
-if (process.env.NODE_ENV === 'test') {
-  // Need to ignore for cjs build.
-  // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-  // @ts-ignore
-  await BarretenbergSync.initSingleton();
-}
+// If we're in ESM environment, use top level await. CJS users need to call it manually.
+// Need to ignore for cjs build.
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+await BarretenbergSync.initSingleton(); // POSTPROCESS ESM ONLY