fix(issue): log proper message when filtering issues by milestone

In the case where we can't find the milestone we should log a helpful message
and bail before trying to list the issues.

fix #703

.vscode/launch.json

@@ -9,15 +9,7 @@
             "type": "node",
             "request": "launch",
             "runtimeArgs": ["-r", "ts-node/register"],
-            "args": [
-                "${workspaceFolder}/src/debug.ts",
-                "re",
-                "-c",
-                "-u",
-                "Product",
-                "--repo",
-                "service-lumin"
-            ],
+            "args": ["${workspaceFolder}/src/debug.ts", "is", "--milestone", "Milestone 5"],
             // "args": ["${workspaceFolder}/src/debug.ts", "ji", "LWM-117", "--status"],
             "console": "integratedTerminal"
         },

README.md

@@ -785,10 +785,10 @@ gh is --list --state closed
 gh is --list --date "dddd, MMMM Do YYYY, h:mm:ss a"
 ```
 
--   List issues filtered by milestone.
+-   List issues filtered by milestone title.
 
 ```
-gh is --list --milestone 1
+gh is --list --milestone "milestone title"
 ```
 
 -   List issues that contains labels `todo` and `bug`.

src/cmds/issue.ts

@@ -294,6 +294,13 @@ async function list(options, user, repo) {
             .filter(milestone => options.milestone === milestone.title)
             .map(milestone => milestone.number)[0]
 
+        if (!milestoneNumber) {
+            logger.log(
+                `No issues found with milestone title: ${logger.colors.red(options.milestone)}`
+            )
+            return
+        }
+
         payload.milestone = `${milestoneNumber}`
     }