fix: add better error messages for wasip1 flags

Signed-off-by: Andrew Steurer <94206073+asteurer@users.noreply.github.com>

Author: asteurer

src/cmd_build.rs

@@ -66,7 +66,7 @@ pub fn build_module(
     ];
 
     let output = if only_wasip1 {
-        unimplemented!();
+        unimplemented!("Building wasip1 Go apps isn't supported quite yet.");
         // TODO: for when/if we decide to allow users to build wasm modules without componentizing them
         #[allow(unreachable_code)]
         Command::new(&go)

src/cmd_test.rs

@@ -74,7 +74,7 @@ pub fn build_test_module(
             .env("GOARCH", "wasm")
             .output()?
     } else {
-        unimplemented!();
+        unimplemented!("Please use the --wasip1 flag when building unit tests");
 
         // TODO: for when we figure out how wasip2 tests are to be run
         #[allow(unreachable_code)]