Add common issues to if node

docs/integrations/builtin/core-nodes/n8n-nodes-base.if/common-issues.md

@@ -0,0 +1,27 @@
+---
+#https://www.notion.so/n8n/Frontmatter-432c2b8dff1f43d4b1c8d20075510fe4
+title: If node common issues 
+description: Documentation for common issues and questions in the If node in n8n, a workflow automation platform. Includes details of the issue and suggested solutions.
+contentType: integration
+priority: high
+---
+
+# If node common issues
+
+Here are some common errors and issues with the [If node](/integrations/builtin/core-nodes/n8n-nodes-base.if/) and steps to resolve or troubleshoot them.
+
+## Can't get data for expression
+
+This error occurs when the If node can't retrieve the data referenced by an expression. This happens when n8n tries to find an item through [item linking](/data/data-mapping/data-item-linking/) but runs into problems.
+
+For example, this JSON references the parameters of the input data. This error will display if you test this step without connecting it to another node:
+
+```javascript
+{
+  "my_field_1": {{ $input.params }}
+}
+```
+
+To troubleshoot this problem, see the [item linking errors](/data/data-mapping/data-item-linking/item-linking-errors/) page to understand how to reference data from nodes that don't include pairing information.
+
+--8<-- "_snippets/integrations/referenced-node-unexecuted.md"

docs/integrations/builtin/core-nodes/n8n-nodes-base.if.md → docs/integrations/builtin/core-nodes/n8n-nodes-base.if/index.md

@@ -1,6 +1,6 @@
 ---
 #https://www.notion.so/n8n/Frontmatter-432c2b8dff1f43d4b1c8d20075510fe4
-title: If
+title: If node
 description: Documentation for the If node in n8n, a workflow automation platform. Includes guidance on usage, and links to examples.
 priority: critical
 tags:
@@ -12,7 +12,7 @@ hide:
   - tags
 ---
 
-# If
+# If node
 
 Use the If node to split a workflow conditionally based on comparison operations.
 
@@ -49,3 +49,6 @@ If you need more than two conditional outputs, use the [Switch node](/integratio
 
 --8<-- "_snippets/integrations/builtin/core-nodes/data-types.md"
 
+## Common issues
+
+For common questions or issues and suggested solutions, refer to [Common Issues](/integrations/builtin/core-nodes/n8n-nodes-base.if/common-issues/).

mkdocs.yml

@@ -379,7 +379,9 @@ nav:
         - HTTP Request:
           - HTTP Request: integrations/builtin/core-nodes/n8n-nodes-base.httprequest/index.md
           - Common issues: integrations/builtin/core-nodes/n8n-nodes-base.httprequest/common-issues.md
-        - integrations/builtin/core-nodes/n8n-nodes-base.if.md
+        - If:
+          - If: integrations/builtin/core-nodes/n8n-nodes-base.if/index.md
+          - Common issues: integrations/builtin/core-nodes/n8n-nodes-base.if/common-issues.md
         - integrations/builtin/core-nodes/n8n-nodes-base.jwt.md
         - integrations/builtin/core-nodes/n8n-nodes-base.ldap.md
         - integrations/builtin/core-nodes/n8n-nodes-base.limit.md