Don't run encoding check if it wasn't provided.

dcherian · dcherian · commit 942e1dd677f2 · 2024-05-08T08:09:51.000-06:00
diff --git a/xarray/backends/api.py b/xarray/backends/api.py
@@ -1684,7 +1684,7 @@ def to_zarr(
                 f"``region`` with to_zarr(), got {append_dim} in both"
             )
 
-    if mode in ["a", "a-", "r+"]:
+    if encoding and mode in ["a", "a-", "r+"]:
         existing_var_names = set(zstore.zarr_group.array_keys())
         for var_name in existing_var_names:
             if var_name in encoding:

Original file line number	Diff line number	Diff line change
`@@ -1684,7 +1684,7 @@ def to_zarr(`
`1684`	`1684`	f"``region`` with to_zarr(), got {append_dim} in both"
`1685`	`1685`	`)`
`1686`	`1686`
`1687`		`- if mode in ["a", "a-", "r+"]:`
	`1687`	`+ if encoding and mode in ["a", "a-", "r+"]:`
`1688`	`1688`	`existing_var_names = set(zstore.zarr_group.array_keys())`
`1689`	`1689`	`for var_name in existing_var_names:`
`1690`	`1690`	`if var_name in encoding:`