fix: check for null chunk ptr (#127)

Author: taegyunkim

echion/stack_chunk.h

@@ -56,7 +56,7 @@ void StackChunk::update(_PyStackChunk* chunk_addr)
 
     origin = chunk_addr;
     // if data_size is not enough, reallocate
-    if (chunk.size > data_capacity)
+    if (chunk.size > data_capacity || data.get() == nullptr)
     {
         data_capacity = chunk.size;
         char* new_data = (char*)realloc(data.get(), data_capacity);
@@ -92,6 +92,11 @@ void* StackChunk::resolve(void* address)
 {
     _PyStackChunk* chunk = (_PyStackChunk*)data.get();
 
+    if (chunk == nullptr)
+    {
+        return address;
+    }
+
     // Check if this chunk contains the address
     if (address >= origin && address < (char*)origin + chunk->size)
         return (char*)chunk + ((char*)address - (char*)origin);