feat: Typescript for API layer (#817)

Co-authored-by: Philip Korsholm <88927411+pKorsholm@users.noreply.github.com>
Co-authored-by: Zakaria El Asri <33696020+zakariaelas@users.noreply.github.com>
Co-authored-by: Kasper Fabricius Kristensen <45367945+kasperkristensen@users.noreply.github.com>
Co-authored-by: Philip Korsholm <philip.korsholm@hotmail.com>
Co-authored-by: Sebastian Rindom <seb@medusa-commerce.com>

packages/medusa-interfaces/src/base-service.js

@@ -21,6 +21,11 @@ class BaseService {
   buildQuery_(selector, config = {}) {
     const build = (obj) => {
       const where = Object.entries(obj).reduce((acc, [key, value]) => {
+        // Undefined values indicate that they have no significance to the query. 
+        // If the query is looking for rows where a column is not set it should use null instead of undefined
+        if (typeof value === "undefined") {
+          return acc
+        }
         switch (true) {
           case value instanceof FindOperator:
             acc[key] = value