Add missing types

v-next/hardhat/src/internal/cli/error-handler.ts

@@ -64,7 +64,7 @@ interface ErrorMessages {
  */
 export function printErrorMessages(
   error: unknown,
-  print = console.error,
+  print: (message: string) => void = console.error,
 ): void {
   const showStackTraces =
     process.argv.includes("--show-stack-traces") ||
@@ -81,7 +81,7 @@ export function printErrorMessages(
   print("");
 
   if (showStackTraces) {
-    print(error instanceof Error ? error.stack : error);
+    print(error instanceof Error ? `${error.stack}` : `${error}`);
     if (postErrorStackTraceMessage !== undefined) {
       print("");
       print(postErrorStackTraceMessage);

v-next/hardhat/test/helpers/env-vars.ts

@@ -18,7 +18,7 @@ export function createTestEnvManager() {
   });
 
   return {
-    setEnvVar(name: string, value: string | undefined) {
+    setEnvVar(name: string, value: string | undefined): void {
       // Before setting a new value, save the original value if it hasn't been saved yet
       if (!changes.has(name)) {
         originalValues.set(name, process.env[name]);