fix collect_data

README.md

@@ -7,8 +7,8 @@ SPDX-License-Identifier: Apache-2.0
 <table>
   <tr>
     <td>
-      <a href="readme/pina_logo.png">
+      <a href="https://github.com/mathLab/PINA/raw/master/readme/pina_logo.png">
-        <img src="readme/pina_logo.png"
+        <img src="https://github.com/mathLab/PINA/raw/master/readme/pina_logo.png"
              alt="PINA logo"
              style="width: 220px; aspect-ratio: 1 / 1; object-fit: contain;">
       </a>

pina/problem/abstract_problem.py

@@ -337,6 +337,10 @@ class AbstractProblem(metaclass=ABCMeta):
                 # If the condition does not have a domain attribute, store
                 # the input and target points
                 keys = condition.__slots__
-                values = [getattr(condition, name) for name in keys]
+                values = [
+                    getattr(condition, name)
+                    for name in keys
+                    if getattr(condition, name) is not None
+                ]
                 data[condition_name] = dict(zip(keys, values))
         self._collected_data = data

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pina-mathlab"
-version = "0.2.5"
+version = "0.2.4"
 description = "Physic Informed Neural networks for Advance modeling."
 readme = "README.md"
 authors = [