Use variable name in all exceptions raised in as_variable (#7995)

* Use variable name in all exceptions raised in `as_variable`

This is more consistent with the other exceptions raised in this
function, and helps to more quickly diagnose issues when e.g. creating
datasets

* Add `as_variable` change to `whats-new`

Author: ZedThree

doc/whats-new.rst

@@ -42,6 +42,8 @@ Documentation
 Internal Changes
 ~~~~~~~~~~~~~~~~
 
+- :py:func:`as_variable` now consistently includes the variable name in any exceptions
+  raised. (:pull:`7995`). By `Peter Hill <https://github.com/ZedThree>`_
 
 .. _whats-new.2023.07.0:
 

xarray/core/variable.py

@@ -125,17 +125,15 @@ def as_variable(obj, name=None) -> Variable | IndexVariable:
     elif isinstance(obj, tuple):
         if isinstance(obj[1], DataArray):
             raise TypeError(
-                "Using a DataArray object to construct a variable is"
+                f"Variable {name!r}: Using a DataArray object to construct a variable is"
                 " ambiguous, please extract the data using the .data property."
             )
         try:
             obj = Variable(*obj)
         except (TypeError, ValueError) as error:
-            # use .format() instead of % because it handles tuples consistently
             raise error.__class__(
-                "Could not convert tuple of form "
-                "(dims, data[, attrs, encoding]): "
-                "{} to Variable.".format(obj)
+                f"Variable {name!r}: Could not convert tuple of form "
+                f"(dims, data[, attrs, encoding]): {obj} to Variable."
             )
     elif utils.is_scalar(obj):
         obj = Variable([], obj)
@@ -154,7 +152,7 @@ def as_variable(obj, name=None) -> Variable | IndexVariable:
         obj = Variable(name, data, fastpath=True)
     else:
         raise TypeError(
-            "unable to convert object into a variable without an "
+            f"Variable {name!r}: unable to convert object into a variable without an "
             f"explicit list of dimensions: {obj!r}"
         )