Add fluent getters to Chat Completion

public/scripts/PromptManager.js

@@ -2,24 +2,39 @@ import {countTokens} from "./openai.js";
 import {DraggablePromptListModule as DraggableList} from "./DraggableList.js";
 import {substituteParams} from "../script.js";
 
+// OpenAI API chat message handling
+// const map = [{identifier: 'example', message: {role: 'system', content: 'exampleContent'}}, ...];
 const ChatCompletion = {
     new() {
         return {
             map: [],
             add(identifier, message) {
                 this.map.push({identifier: identifier, message: message})
+                return this;
             },
             insertBefore(identifier, insertIdentifier, insert) {
                 const index = this.getMessageIndex(identifier);
+                if (index === -1) throw new Error(`Identifier ${identifier} not found`);
                 this.map.splice(index, 0, {identifier: insertIdentifier, message: insert});
+                return this;
             },
             insertAfter(identifier, insertIdentifier, insert) {
                 const index = this.getMessageIndex(identifier);
+                if (index === -1) throw new Error(`Identifier ${identifier} not found`);
                 this.map.splice(index + 1, 0, {identifier: insertIdentifier, message: insert});
+                return this;
             },
             replace(identifier, replacement) {
                 const index = this.getMessageIndex(identifier);
+                if (index === -1) throw new Error(`Identifier ${identifier} not found`);
                 this.map[index] = {identifier: identifier, message: replacement};
+                return this;
+            },
+            remove(identifier) {
+                const index = this.getMessageIndex(identifier);
+                if (index === -1) throw new Error(`Identifier ${identifier} not found`);
+                this.map.splice(index, 1);
+                return this;
             },
             getMessageIndex(identifier) {
                 const index = this.map.findIndex(message => message.identifier === identifier)