Enhance the ugly error in constructor when no data passed (#8920)

* Enhance the ugly error in constructor when no data passed

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Fix mypy issues

* Get unpacked data to be used downstream

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

xarray/core/variable.py

@@ -123,13 +123,18 @@ def as_variable(
     if isinstance(obj, Variable):
         obj = obj.copy(deep=False)
     elif isinstance(obj, tuple):
-        if isinstance(obj[1], DataArray):
+        try:
+            dims_, data_, *attrs = obj
+        except ValueError:
+            raise ValueError(f"Tuple {obj} is not in the form (dims, data[, attrs])")
+
+        if isinstance(data_, DataArray):
             raise TypeError(
                 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)
+            obj = Variable(dims_, data_, *attrs)
         except (TypeError, ValueError) as error:
             raise error.__class__(
                 f"Variable {name!r}: Could not convert tuple of form "