Restucture wasm module, return a normal TSLanguage from load_language

lib/src/wasm/wasmtime/error.h

@@ -0,0 +1,55 @@
+/**
+ * \file wasmtime/error.h
+ *
+ * \brief Definition and accessors of #wasmtime_error_t
+ */
+
+#ifndef WASMTIME_ERROR_H
+#define WASMTIME_ERROR_H
+
+#include <wasm.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \typedef wasmtime_error_t
+ * \brief Convenience alias for #wasmtime_error
+ *
+ * \struct wasmtime_error
+ * \brief Errors generated by Wasmtime.
+ * \headerfile wasmtime/error.h
+ *
+ * This opaque type represents an error that happened as part of one of the
+ * functions below. Errors primarily have an error message associated with them
+ * at this time, which you can acquire by calling #wasmtime_error_message.
+ *
+ * Errors are safe to share across threads and must be deleted with
+ * #wasmtime_error_delete.
+ */
+typedef struct wasmtime_error wasmtime_error_t;
+
+/**
+ * \brief Deletes an error.
+ */
+WASM_API_EXTERN void wasmtime_error_delete(wasmtime_error_t *error);
+
+/**
+ * \brief Returns the string description of this error.
+ *
+ * This will "render" the error to a string and then return the string
+ * representation of the error to the caller. The `message` argument should be
+ * uninitialized before this function is called and the caller is responsible
+ * for deallocating it with #wasm_byte_vec_delete afterwards.
+ */
+WASM_API_EXTERN void wasmtime_error_message(
+    const wasmtime_error_t *error,
+    wasm_name_t *message
+);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif // WASMTIME_ERROR_H