Move find_spec to top of file

Author: ValerianRey

src/torchjd/aggregation/cagrad.py

@@ -1,5 +1,12 @@
 from importlib.util import find_spec
 
+# Check that the clarabel solver is installed
+if find_spec("clarabel") is None:
+    raise ModuleNotFoundError(
+        "CAGrad requires the clarabel solver, but it is not installed. Please run"
+        "`pip install torchjd[cagrad]`."
+    )
+
 import cvxpy as cp
 import numpy as np
 import torch
@@ -8,13 +15,6 @@
 from ._gramian_utils import compute_gramian, normalize
 from .bases import _WeightedAggregator, _Weighting
 
-# Check that the clarabel solver is installed
-if find_spec("clarabel") is None:
-    raise ModuleNotFoundError(
-        "CAGrad requires the clarabel solver, but it is not installed. Please run"
-        "`pip install torchjd[cagrad]`."
-    )
-
 
 class CAGrad(_WeightedAggregator):
     """

src/torchjd/aggregation/nash_mtl.py

@@ -26,19 +26,19 @@
 
 from importlib.util import find_spec
 
-import cvxpy as cp
-import numpy as np
-import torch
-from cvxpy import Expression
-from torch import Tensor
-
 # Check that the ecos solver is installed
 if find_spec("ecos") is None:
     raise ModuleNotFoundError(
         "NashMTL requires the ecos solver, but it is not installed. Please run"
         "`pip install torchjd[nash_mtl]`."
     )
 
+import cvxpy as cp
+import numpy as np
+import torch
+from cvxpy import Expression
+from torch import Tensor
+
 from .bases import _WeightedAggregator, _Weighting