Use Expect in EOnumber$EOas_i64

eo-runtime/src/main/java/EOorg/EOeolang/EOnumber$EOas_i64.java

@@ -33,6 +33,7 @@
 import org.eolang.BytesOf;
 import org.eolang.Data;
 import org.eolang.Dataized;
+import org.eolang.Expect;
 import org.eolang.PhDefault;
 import org.eolang.Phi;
 import org.eolang.XmirObject;
@@ -52,7 +53,10 @@ public Phi lambda() {
             0,
             new Data.ToPhi(
                 new BytesOf(
-                    new Dataized(this.take(Attr.RHO)).asNumber().longValue()
+                    Expect.at(this, Attr.RHO)
+                        .that(phi -> new Dataized(phi).take(Long.class))
+                        .otherwise("must be a number")
+                        .it()
                 ).take()
             )
         );

eo-runtime/src/main/java/EOorg/EOeolang/EOnumber$EOplus.java

@@ -28,9 +28,9 @@
  */
 package EOorg.EOeolang; // NOPMD
 
+import org.eolang.AtVoid;
 import org.eolang.Atom;
 import org.eolang.Attr;
-import org.eolang.AtVoid;
 import org.eolang.Data;
 import org.eolang.Dataized;
 import org.eolang.Expect;

eo-runtime/src/test/java/EOorg/EOeolang/EOnumber$EOas_i64Test.java

@@ -0,0 +1,68 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016-2025 Objectionary.com
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/*
+ * @checkstyle PackageNameCheck (10 lines)
+ * @checkstyle TrailingCommentCheck (3 lines)
+ */
+package EOorg.EOeolang; // NOPMD
+
+import org.eolang.Attr;
+import org.eolang.Data;
+import org.eolang.Dataized;
+import org.eolang.ExAbstract;
+import org.eolang.PhWith;
+import org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Test case for {@link EOnumber$EOas_i64}.
+ *
+ * @since 0.51
+ * @checkstyle TypeNameCheck (3 lines)
+ */
+@SuppressWarnings("PMD.AvoidDollarSigns")
+final class EOnumber$EOas_i64Test {
+
+    @Test
+    void throwsCorrectErrorForRhoAttr() {
+        MatcherAssert.assertThat(
+            "the message in the error is correct",
+            Assertions.assertThrows(
+                ExAbstract.class,
+                () -> new Dataized(
+                    new PhWith(
+                        new EOnumber$EOas_i64(),
+                        Attr.RHO,
+                        new Data.ToPhi("string")
+                    )
+                ).take(),
+                "EOnumber must be a number"
+            ).getMessage(),
+            Matchers.equalTo("the 'ρ' attribute must be a number")
+        );
+    }
+}