[lightbeam] replace asserts by Errors in module.rs / translate_only (#713)

* replace assert by Errors

* add better errors message module.rs

crates/lightbeam/src/module.rs

@@ -7,7 +7,7 @@ use cranelift_codegen::{
     isa,
 };
 use memoffset::offset_of;
-use more_asserts::assert_le;
+
 use std::{convert::TryInto, mem};
 use thiserror::Error;
 use wasmparser::{FuncType, MemoryType, ModuleReader, SectionCode, Type};
@@ -563,15 +563,19 @@ pub fn translate_only(data: &[u8]) -> Result<TranslatedModule, Error> {
         let memories = section.get_memory_section_reader()?;
         let mem = translate_sections::memory(memories)?;
 
-        assert_le!(
-            mem.len(),
-            1,
-            "Multiple memory sections not yet unimplemented"
-        );
+        if mem.len() > 1 {
+            return Err(Error::Input(
+                "Multiple memory sections not yet implemented".to_string(),
+            ));
+        }
 
         if !mem.is_empty() {
             let mem = mem[0];
-            assert_eq!(Some(mem.limits.initial), mem.limits.maximum);
+            if Some(mem.limits.initial) != mem.limits.maximum {
+                return Err(Error::Input(
+                    "Custom memory limits not supported in lightbeam".to_string(),
+                ));
+            }
             output.memory = Some(mem);
         }
 
@@ -642,7 +646,11 @@ pub fn translate_only(data: &[u8]) -> Result<TranslatedModule, Error> {
         translate_sections::data(data)?;
     }
 
-    assert!(reader.eof());
+    if !reader.eof() {
+        return Err(Error::Input(
+            "Unexpected data found after the end of the module".to_string(),
+        ));
+    }
 
     Ok(output)
 }