#3542 output a clearer message when too many attributes are passed.

eo-runtime/src/main/java/org/eolang/AtWithRho.java

@@ -71,4 +71,12 @@ public Phi get() {
     public void put(final Phi phi) {
         this.origin.put(phi);
     }
+
+    /**
+     * Returns the original attribute.
+     * @return The original attribute
+     */
+    public Attr getOrigin() {
+        return this.origin;
+    }
 }

eo-runtime/src/main/java/org/eolang/PhDefault.java

@@ -140,7 +140,16 @@ public boolean hasRho() {
 
     @Override
     public void put(final int pos, final Phi object) {
-        this.put(this.attr(pos), object);
+        final String name = this.attr(pos);
+        if (!(((AtWithRho) this.attrs.get(name)).getOrigin() instanceof AtVoid)) {
+            throw new ExReadOnly(
+                String.format(
+                    "Can't put attribute with position %d because it's not void one",
+                    pos
+                )
+            );
+        }
+        this.put(name, object);
     }
 
     @Override

eo-runtime/src/test/java/org/eolang/PhDefaultTest.java

@@ -23,6 +23,7 @@
  */
 package org.eolang;
 
+import EOorg.EOeolang.EOnumber;
 import com.yegor256.Together;
 import java.security.SecureRandom;
 import org.cactoos.set.SetOf;
@@ -488,6 +489,19 @@ void doesNotCalculateRandomTwice() {
         );
     }
 
+    @Test
+    void failsCorrectlyWhenTooManyAttributesPut() {
+        MatcherAssert.assertThat(
+            "the message explains what's going on",
+            Assertions.assertThrows(
+                ExAbstract.class,
+                () -> new EOnumber().put(1, new Data.ToPhi(1)),
+                "fails when trying to set attribute with too big position"
+            ).getMessage(),
+            Matchers.equalTo("Can't put attribute with position 1 because it's not void one")
+        );
+    }
+
     /**
      * Rnd.
      * @since 0.1.0